1. Field of the Invention
The present invention relates to a technique for installing a program.
2. Description of the Related Art
In information processors that implement various functions by executing programs, it is possible to change (that is, increase and decrease) the number of functions by changing the number of programs to be installed. Even after purchasing information processors, users are allowed to use desired functions by purchasing and installing programs that provide the functions.
On the other hand, by way of example, Japanese Laid-Open Patent Application No. 2000-293365 teaches (a) storing a previously downloaded version of the program in order to restore the original configuration in case there is a problem in the upgrade of the program; and (b) invalidating the current version of the program and validating the previous version of the program at the time of downgrading.